Longman Lindsey is one of the largest independent acoustical consultancy firms in the United States, serving the construction industry.
We provide informed acoustical solutions for design professionals at each step of the creative process by conducting thorough investigation and analysis, while bringing our unrivaled experience to every project on which we work. Longman Lindsey is known for providing concise, straight-forward, cost-effective recommendations to every acoustical design.
The partners of Longman Lindsey—John Longman, Stephen Lindsey, Patricia Scanlon, and Ken Shook —have over 100 years of combined acoustical consulting experience and have grown the practice into one of the largest and prominent acoustical consulting groups in the United States.
Architectural acoustics is often not visible to the eye, but is an incredibly important part of building design. This is the general term for the science of controlling sound and vibration transmission through a building’s design. Depending on the project type, services can include reducing environmental noise through the building envelope, isolating mechanical and other building systems from occupants, maintaining acoustic privacy from vertically and horizontally adjacent spaces, reducing impact noise transmission and footfall between floors, providing the appropriate balance between sound absorptive and reflective surface finishes for specific uses, and designing interior environments to enhance speech privacy and reduce distractions for the occupants.
The elements of each architectural acoustic design are unique to a particular project and its goals, budget, and aesthetic. To avoid potential costly and challenging surprises during the construction process, it is important to factor in the acoustics of the project or building structure as early as possible during design phases. We offer solutions at the start of your project to avoid changes once the project is further in design, eliminating the potential for both wasted time and money. We often verify project design elements—such as noise reduction across a partition or impact isolation through a floor assembly—during mockup tests of sample constructions.
Room acoustics is the experience of a listener in a given environment, which is influenced by the room volume, shape, and location of sound absorptive and sound reflective surfaces. Depending on the needs of a particular space—a recording studio, for example, as compared to a cathedral or airport terminal—the recommendations for surface finishes, electronic sound reinforcement equipment, and placement will be very different. Even more critical are spaces often termed “multi-purpose” as they are needed to support a variety of uses. How do you make the same space work for the intelligibility of simple spoken word, yet also function for a musical performance? Through our assessments using reverberation calculations and modeling techniques, we are able to design a space that satisfies every desired function of a room.
One of the most important characteristics of a given room is the background noise level, which often influences whether or not the space is suitable for its intended functionality. Controlling noise and vibration generated by equipment serving a space, or located in close proximity to it, is an essential element of building design. This applies to a wide variety of project types, whether a fifty-story commercial office building or a residential tower.
The first part of our review of mechanical systems is to understand the intended use of the spaces being considered. Then, we work with the design team to optimize equipment selections to minimize the need for additional noise control and provide an overall system review throughout the design process. We offer recommendations on how to reduce noise from HVAC systems and create a space that complies with appropriate standards. In projects where the same piece of equipment is used repeatedly, or the same main equipment is installed on each floor, we often organize mockup testing to ensure the noise levels are consistent with manufacturer’s projections, and the resulting noise levels comply with design requirements.
The progression towards more lightweight structures has created buildings that are more susceptible to transmit vibration from rotating mechanical equipment, as well as from activities associated with open floor plans devoid of traditional office structures, fitness centers, and gymnasiums. This vibration can be amplified or mitigated depending on the placement of the source and the isolation measures.
A vibration isolator is a flexible device or material used to resiliently support any type of vibrating machinery or equipment, thereby reducing the vibration energy potentially transmitted to the building structure. The same concept applies when considering a fitness center space where the result of a group exercise class or multiple people using impact generating equipment introduces vibration energy into the building structure that will readily transmit if not properly mitigated. Common examples of vibration isolators are conventional wound springs, elastomeric pads, air springs, and wire rope springs. We determine which types of vibration isolators are most effective for mechanical devices, exercise, and fitness equipment, and will provide this guidance to the project team and engineers.
Technology has touched everyone’s life, including that of the acoustician. Modeling programs enable us to recreate an environment long before construction so that we can fine-tune acoustical solutions—be it a space used for performances and musical productions, or how noise will be transmitted from a building or source to the neighboring community. This is an incredibly helpful tool when working with project teams and end users, to the extent that they can virtually hear how various design options will impact speech intelligibility or sound quality in the given location. It also helps us convey the acoustical impact of a proposed project to a planning board or municipality, as we can situate noise sources such as mechanical equipment or roadways and then map the resulting sound levels at receiver locations or across varying distances.
Workplace design continues to trend away from enclosed private offices to more open spaces that have fewer barriers to encourage collaboration. Sustainability goals have also reduced the amount of finishes provided in typical offices, such as ceiling tiles, carpet, and wall panels, all of which provide sound absorption and have increased the use of glass to allow natural light to permeate through offices. While these changes may have resulted in improved satisfaction in areas like lighting, feedback on acoustic quality and privacy regularly lags behind.
Sound masking offers an opportunity to improve speech privacy by providing a constant elevated background noise level. This can be applicable to open plan spaces and private offices, where sound masking is a way to boost privacy without significant changes to office construction. We have designed traditional systems with loudspeakers in ceiling or raised floor plenums, as well as actuator type speakers, which resonate on glass, gypsum board, or other solid surfaces. We work with clients and the design team to assess privacy in existing office environments, project levels in the proposed new space, then assess the benefits of sound masking. If sound masking is deemed appropriate, we design the system, taking into account structure, mechanical equipment, and ceiling types. Our services extend through the construction phase, during which we review the installation and tune the system to ensure the desired levels are achieved prior to occupancy.
Everyone has experienced environmental noise transmission in one form or another from elevated train tracks, highway traffic, overhead aircraft, or exterior mechanical equipment. Most cities and municipalities have developed standards and requirements to outline acceptable noise levels. We interpret these requirements into design solutions, which may include appropriate window glazing, sound barriers, and equipment enclosures, as well as work with design teams to establish the acoustic criteria suitable for their particular project. This is especially critical for data center projects where equipment must operate 24/7, typically with significant quantities of noise-producing cooling and emergency power equipment. During the design phases of a project, we will investigate simple and practical solutions. Many times the easiest solution is to select a type or size equipment, or even its location, in a way that minimizes the need for additional noise control.
Any type of project can fall into the category of troubleshooting: sound transmission between neighbors, noisy exhaust fan violating local code, or fitness center resulting in impact transmission to building tenants. With over 90 years of combined experience, we have seen every type of project imaginable and bring this expertise when called to investigate a problem. Sometimes there is an unexplained noise source, and we will work to find the likely suspect and conduct further investigation. Other times we will visit a recently completed office, where there is an abundance of reflected sound energy, and discuss the most suitable options for improvement, knowing that cost and ease of installation are critical when working in a finished, occupied space.
We provide expert knowledge based on decades of experience in the field to various product developers and manufacturers. We test equipment, review the noise and/or vibration it generates, and advise on how to improve its performance. Similarly with a floor underlayment material, we measure the noise reduction it affords, and advise the manufacturer on aspects of the performance that may be improved.
There are specific ratings and ASTM test procedures used to quantify performance, be it sound levels generated by mechanical or ASTC/NIC ratings for partition assemblies. We understand the test standards and have the precision equipment required to undertake such testing. This enables us to work with manufacturers, measure their product performance, and verify they attain the relevant metric.